Electrodeposition of nickel



United States Patent Ofi 3,220,940 Patented Nov. 30, 1965 3,220,940 ELECTRODEPOSITION OF NICKEL Henry Brown, Huntington Woods, Donald H. Becking, Birmingham, and Richard M. Stevenson, Grosse Pointe Woods, Mich., assignors to The Udylite Research Corporation, Detroit, Mich., a corporation of Michigan No Drawing. Filed Feb. 7, 1962, Ser. No. 171,566

Claims. (Cl. 204-49) This invention relates to the electrodeposition of nickel from aqueous acidic baths.

The object of this invention is the production of semibright low stress, fine-grained nickel plate.

While many aryl sulfonic acids and aryl sulfon-compounds have been found to produce fine-grained semibright nickel plate from Watts baths, there is nevertheless need for improved results. For example, while 0- benzoyl sulfimide, is one of the best, if not the best, of the aryl sulfon-compounds, in producing semi-bright finegrained ductile nickel, it nevertheless makes the Watts bath sensitive to quite low concentrations (0.03 gram per liter) of dissolved zinc impurity, causing dark streaks in the low current density areas.

We have now found that by replacing the imide hydrogen of o-benzoyl sulfimide with a short chain aliphatic sulfonic acid radical, the sensitivity of the Watts bath to low concentrations of zinc ions is eliminated. Thus the nickel baths containing these new derivatives of o-benzoyl sulfimide can be used much more effectively in the plating of zinc die castings or other zinc surfaces, which are first copper, brass or nickel plated from an alkaline bath, without serious problems arising from concentrations of zinc impurity accumulating in the Watts bath to values higher than about 0.03 gram per liter. Actually with these new improved sulfonic acid compounds, concentrations of zinc ion may reach values as high as about 0.2 gram per liter without any darkness in the low current density areas. In Table I are listed a number of representative examples of these new compounds which are encompassed by the following formula (or the Ni, Co, Na, K, Li, Mb, etc., isulfonate salts) wherein R is selected from the substituents H, OH, Cl, Br, 80 1-1, and CH n is an integer from 1 to 4 inclusive, n is 0 or 1, n is zero, 1, or 2, and when n is 0, n is 0.

TABLE IC0ntinued Useful Concentration grams/liter 2 S 11 3 NCH2OHCH2SO3H 0.1-saturation.

C ll 0 4 N0I-IzCH2OH2SO3H (ll-saturation.

C H O 5 NC2H4O Cali-1803B: 0.1-saturation.

O H O O 2 S (I31 6 NC H2 C I-I-C HgS O N2; (ll-saturation.

C II 0 Not only is the effectiveness of o-benzoyl sulfimide in Watts nickel baths improved by the above substitution of the short chain aliphatic sulfonic acid radical for the imide hydrogen, but also improved by similar imide hydrogen substitution are the following very slightly bath soluble compounds designated by the formula QQ Q 3 are much more effective in the acidic nickel baths when the imide hydrogen is replaced by the aliphatic sulfonic radical represented by the following formula this art for such baths. Other buffers of acidic character may be employed, however, such as, for example, formic acid, fluoboric acid and the like, and such may be used either in place of or in conjunction with boric acid. For

B J 5 optimum results, the concentration of bone acid or its I (o)"1 i SO3H equivalent should be above about grams per l1ter,

H a particularly when the baths are operated at elevated temperatures. The baths may include various supplemental in which the symbols R and m, n and n are as previously agents, such as anti-pitting agents, which are now condefined. 10 ventionally employed in this art, and as more particularly In Table II are listed some representative examples suggester hereinafter. of these compounds. Besides the use of these compounds 1n acidic nickel TABLE II Useful Concentration grams/liter on CHzCHCHzSOsH I 1 SOz-NC 0.1-saturation.

C2H4SO3H I I i 2 C1 SO2-NC 0.1-saturation.

CZHGSOQH l t 3 CH3C -SO2NC 0.1-saturation.

CzH4O C2H4SO3H l i 4 SO2NCC1 0.1-saturation.

sioarr OH CH-CI-I2SO H I i 5 SO2NO 0.1-saturation.

Thus, this invention consists of the use in acidic nickel baths of the sulfonic and/or sulfonates covered by the more general formula n is zero, 1 or 2, and when n is zero then n is zero.

The dotted line signifies that A may be separate rings or a single ring, for example, in the N-substituted compounds of Table I, the A substituent attached to SO and CO is a common substituent, namely a single benzene ring.

The aqueous nickel plating baths which are improved by the use of the addition agents of this invention may be of various types but, in all cases, are acidic in character. The preferred baths are those of the Watts type or modifications thereof. The nickel salts may comprise nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate, or other nickel salts or mixtures of any two or more of said nickel salts, preferably in conjunction with buffer materials as, for example, boric acid, the preferred buffer. The amounts of such nickel salts which may be employed are quantities which are now conventional in plating baths to give low stress or compressively stressed, fine-grained, semi-bright nickel plate which is useful in decorative plating where a satin or a semi-bright finish is desired, there are also many engineering uses, such as in electroforming, magnetic films, printed circuits, etc., where low stress and fine-grained plate is important. Additionally, there is the important use of these new sulfonic acid compounds together with strongly unsaturated compounds or amines to produce brilliant, high leveling nickel plate from acidic nickel plating baths.

The sulfonic acid compounds of this invention can be used in low concentrations of about 0.05 gram per liter with improved results in the low current density plating ranges. In general for the Widest plating range, about 0.1 g./l. to 3 grams per liter is the optimum concentration range for these sulfonic compounds. These sulfonic compounds have, however, no critical upper limit of concentration, and can be used up to saturation concentration values. They are completely compatible in the nickel baths with other organic sulfon-compounds such as those shown in Table II of US. 2,800,442, issued July 23, 1957. They are usually prepared as the sodium salt or the nickel salt, and after adding the compounds to the acidic nickel baths, they are present mainly as the nickel salt and the free acid. Concentrations of ferrous salts, such as ferrous sulfate, chloride, or fluoborate may be as high as at least 40 grams per liter ithout harmful effect on the appearance of the plate, and the alloy plates electrodeposited therefrom contain at least 40% of iron. Even higher concentrations of similar cobalt salts may be used in the nickel bath and the appearance of the plate is excellent even when the cobalt is at least 50% of the alloy plate. Moreover, mixtures of cobalt and iron salts can be used to give ternary alloy plates of excellent appearance and properties even when the nickel present in the alloy plate is as low as about 50%.

In the absence of secondary brightening agents such as amines, unsaturated comlpounds, etc., high concentrations of such cations as Na+, Li+, K NH Mg++, may also be present in the nickel baths and good plate can be obtained in the presence of the sulfonic acid compounds of this invention.

The baths as exemplified by A, B, and C can be operated with or without air agitation. It is preferred to use agitation when feasible whether it is air agitation or cathode rod agitation. With very rapid agitation, very high current densities can be used, for example, at least 500 to 1,000 amps/sq. ft. (approximately 50 to 100 amps/ sq. dm.). With air agitation, a low foaming wetting agent such as sodium 2-ethylhexyl sulfate or n-octyl sulfate or a mixture may be used. Without air agitation the longer chain surface-active agents, such as sodium lauryl sulfate, are preferred.

Example A Grams/liter NiSO .6H O 150-400 NiCl .6H O 30-50 H BO 40-45 NC H SOaI-I 0.05-3

pH 2.0 to 5.5, temp. room to 70 C. Av. cathode current density, 0.5 to arnps/ sq. dm.

Example B Grams/liter NiSO .6H O 50-40'0 NiCl .6H O 200- H BO -45 NaBR, 1-6

N-CH CH CH SO H 0.1-4

pH 2.0 to 5.5, temp. room to 70 C. Av. cathode current density, 0.5 to 10 amps/ sq. dm.

Example C Grams/liter NiSO .6H O 150-400 NiCl .6H O 30-100 H BO 40-45 (])H CHgCHCHgSOaH I a Q- -Q pH 1.5 to 6.0, temp. room to 75 C. Av. cathode current density, 0.5 to 10 amps/ sq. dm.

Example D Grams/liter NiSO .6H O -400 NiCl .6H O 250-30 H BO 40-50 pH to 2.8 to 5, temp. 50 to 70 C. Av. Cathode current density, 2 to 10 :amps/ sq. dm.

In particular, the compounds of Tables I and II give further improved fine-grained plate when used in conjunction with about 0.3 to 4 grams per liter of allyl sulfonic acid. In addition, if an unsaturated compound such as N-allyl quinaldinium bromide, polyalkylene amine, or butynoxy ethane sulfonic acid is also added to the nickel bath, a very bright, ductile plate is obtained over a very Wide plating range.

What is claimed is:

1. A bath for electrodepositing fine-grained nickel plate comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fluoborate and nickel sulfamate, and containing dissolved in said nickel plating solution in a concentration of about 0.05 gram per liter to saturation, an organic sulfonic acid compound in accordance with the formula Ii 3. A bath for electrodepositing fine-grained nickel plate in accordance with claim 1 and wherein said sulfonic acid compound is N-CsHeSOaH 4. A bath for electrodepositing fine-grained nickel plate in accordance with claim 1, and wherein said sulfonic acid compound is CH2CHOHCH2SO3H 5. A method for electrodepositing fine-grained nickel comprising the step of electrodepositing nickel from an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fiuoborate, and nickel sulfamate, and containing dissolved in said nickel plating solution in a concentration of about 0.05 gram per liter to saturation, an organic sulfonic acid compound in accordance with the formula 09 i S i N-CgHaSOaH 7. A method for electrodepositing fine-grained nickel in accordance with claim 5, and wherein said sulfonic acid compound is 0 ll 0 8. A method for electrodepositing fine-grained nickel in accordance with claim 5, and wherein said sulfonic acid compound is OHzCHOHOH2S0aH 9. A bath for electrodepositing fine-grained nickel plate comprising an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel =fluoborate and nickel 4 3 sulfamate, and containing dissolved in said nickel plating solution in a concentration of about 0.05 gram per liter to saturation, an organic sulfonic acid compound in accordance with the formula wherein A is selected from the group consisting of the benzene, biphenyl and naphthalene rings, R is selected from the group consisting of H, OH, Cl, Br, SO H and CH n is an integer from 1 to 4 inclusive, n is 0 to 1, n is zero, 1 or 2, and when n is zero then n is zero, and allyl sulfonic acid in a concentration in the range of about 0.3 to 4 grams per liter.

10. A method for electrodepositing fine-grained nickel comprising the step of electrodepositing nickel from an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride, nickel fluoborate, and nickel sulfamate, and containing dissolved in said nickel plating solution in a concentration of about 0.05 gram per liter to saturation, an organic sulfonic acid compound in accordance with the formula References Cited by the Examiner FOREIGN PATENTS 8/1939 Canada. 3/1954 Germany.

JOHN H. MACK, Primary Examiner.

MURRAY TILLMAN, Examiner. 

5. A METHOD FOR ELECTRODEPOSITING FINE-GRAINED NICKEL COMPRISING THE STEP OF ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, NICKEL FLUOBORATE, AND NICKEL SULFAMATE, AND CONTAINING DISSOLVED IN SAID NICKEL PLATING SOLUTION IN A CONCENTRATION OF ABOUT 0.05 GRAM PER LITER TO SATURATION, AN ORGANIC SULFONIC ACID COMPOUND IN ACCORDANCE WITH THE FORMULA 